Temperature-Independent Blood Glucose Measurement

• US 5,968,760 A
• Filed: 11/07/1997
• Issued: 10/19/1999
• Est. Priority Date: 08/13/1986
• Status: Expired due to Fees

• Current Assignee: Lifescan Incorporated (Duv Holding Corporation)
• Original Assignee: Lifescan Incorporated (Duv Holding Corporation)
• Inventors: Phillips, Roger, McGarraugh, Geoffery, Jurik, Franklin A., Underwood, Raymond D.
• Primary Examiner(s): GITOMER, RALPH J
• Application Number:
  US08/965,745
• Time in Patent Office: 711 Days
• Field of Search: 435/14, 435/25, 435/28, 435/805, 422/55-58, 436/169
• US Class Current: 435/14
• CPC Class Codes: C12Q 1/54 involving glucose or galactose
• CPC Class Codes: G01N 2021/4757 Geometry 0/45° or 45/0°
• CPC Class Codes: G01N 21/314 with comparison of measurements at specific and non-specific wavelengths dual wavelength spectrometry G01J3/427
• CPC Class Codes: G01N 21/4738 Diffuse reflection precedence is given to G01N21/55 - G01N21/57 if specular component is taken into consideration, e.g. also for testing fluids, fibrous materials
• CPC Class Codes: G01N 21/8483 Investigating reagent band test-element handling not specific to a test method G01N33/4875; analytical elements specific to chemical analysis of biological material G01N33/52; autometer with reagent band G01N35/04
• CPC Class Codes: G01N 33/52 Use of compounds or compositions for colorimetric, spectrophotometric or fluorometric investigation, e.g. use of reagent paper and including single- and multilayer analytical elements immunological elements G01N33/54386; involving labelled immunochemicals G01N33/58; for haemoglobin or occult blood G01N33/72
• CPC Class Codes: G01N 33/521 Single-layer analytical elements
• CPC Class Codes: G01N 33/523 the element being adapted for a specific analyte
• CPC Class Codes: G01N 33/66 involving blood sugars, e.g. galactose
• CPC Class Codes: G01N 35/1016 Control of the volume dispensed or introduced
• CPC Class Codes: Y02A 90/10 Information and communication technologies [ICT] supporting adaptation to climate change, e.g. for weather forecasting or climate simulation
• CPC Class Codes: Y10S 435/805 Test papers
• CPC Class Codes: Y10S 435/808 Optical sensing apparatus
• CPC Class Codes: Y10S 435/81 Packaged device or kit
• CPC Class Codes: Y10T 436/112499 with sample on test slide
• CPC Class Codes: Y10T 436/144444 Glucose

Abstract

A method for determining the presence of an analyte in a fluid is described along with various components of an apparatus specifically designed to carry out the method. The method involves taking a reflectance reading from one surface of an inert porous matrix impregnated with a reagent that will interact with the analyte to produce a light-absorbing reaction product when the fluid being analyzed is applied to another surface and migrates through the matrix to the surface being read. Reflectance measurements are made at two separate wavelengths in order to eliminate interferences, and a timing circuit is triggered by an initial decrease in reflectance by the wetting of the surface whose reflectance is being measured by the fluid which passes through the inert matrix. Repeatability in insured by a normalization technique performed on the light source before each reading, and an alignment method operated on the reagent strip prior to emplacement on the apparatus. The method and apparatus are particularly suitable for tho measurement of flucose levels in blood without requiring separation of red blood cells from serum or plasma.

Claims

1. A substantially temperature-independent strip and apparatus combination for measuring glucose in a whole blood sample, comprising

(a) a reagent strip for placement into a reflectance reading apparatus, the strip comprising a porous matrix to whose surface the whole blood sample is applied and in which is contained a reagent composition that reacts with glucose in the whole blood sample to develop a color and thereby to cause a measurable reflectance change during a fixed time interval, the reagent composition comprising glucose oxidase, peroxidase, and an MBTH-DMAB (3-methyl-2-benzothiazolinone hydrazone hydrochloride and 3-dimethylaminobenzoic acid) dye indicator;

and

(b) the reflectance reading apparatus comprising a light emitting diode with an emission maximum at about 635 nm for illuminating the matrix and a photodetector for measuring the light reflected from the matrix, whereby increased temperature causes a shift in the diode emission maximum to a longer wavelength, at which the MBTH-DMAB has greater reflectance, which substantially balances faster color development to leave reflectance change during the fixed time interval substantially unaffected.